Cut the train drain

The rail industry can help in the fight to protect the environment and save itself money at the same time, argues Alan Constable.

Saving the environment is a hot topic and different industries are always looking at how they can contribute. The rail industry is no different and a recent study shows that savings can be made in many areas.

Annual electric traction energy consumption across the UK’s rail operations could be cut by about 25 per cent over the next few years, with opportunities for even more in the longer term.

Interfleet was commissioned by the Rail Safety and Standards Board to examine potential traction energy savings/reductions in CO2 emissions in the industry, in particular to see how the rail industry can reduce energy consumption from train operations at the same time as helping the environment.

Working closely with sub-contractors Enotrac and Prof Roger Kemp of Lancaster University, the report’s authors identified about 50 opportunities, which could offer potential CO2 and/or cost savings.

The study identified the losses in power generation and distribution, tracing them through electric train operational and traction systems where energy is consumed or wasted.

A similar breakdown of energy losses and consumption was developed for diesel trains.

Taking into account the relative efficiencies of power stations and diesel engines, in energy terms the consumption of electric and diesel traction are similar. Electric traction does, however, require a more substantial electrical distribution network compared with geographically spread diesel refuelling points.

Within the train systems the consumption and losses are similar, since many diesel trains have state-of-the-art electric drives that are inherently efficient.

However, there is still much more that can be done technically and operationally to save energy. The most promising areas for potential savings in the short to medium term amount to a potential saving of about 15 per cent of the total UK rail traction energy.

One way is to reduce power used by stabled electric trains. For example, some trains are stabled with heating on overnight and air conditioning on during the day in summer. Switching systems off when not necessary or fitting simple control technology will result in sizeable savings for UK train operators and significantly reduce CO2 emissions from power stations.

Optimising train capacity is also an area for further research — initial studies reveal that more should be done. For operational reasons a number of off-peak, inner-London services are operated by eight-car trains, where four would be adequate. However, this increases energy consumption.

Therefore, it would seem that, wherever practical, matching train size to passenger load will produce energy savings, although this would need further studies of operational logistics.

New trains, both diesel and electric, are generally more powerful than older ones, which helps drivers make up time when delays occur but can also result in energy-inefficient driving styles. If new drivers can be trained, and more experienced ones retrained, to drive more energy efficiently using real trains or upgraded simulators, then savings of 5-10 per cent are possible.

The study we carried out also showed that heating and cooling systems consume about 15 per cent of the energy drawn by a train. This load could be reduced through various modifications and adjustments, ranging from changes to thermostat set points to reconfigured air conditioning equipment.

Lighting is also an issue. For example, refurbished high-speed trains (HSTs) now consume more than twice as much lighting energy than the original trains when they were built. Meridian trains consume 77 per cent more lighting energy than the original HSTs they replaced.

Opportunities have been identified where new lighting technology, combined with a reversion to previous accepted lighting levels, could save more than £4m a year in energy costs.

Our findings were consistent with other parallel European studies. But some savings will only be possible with certain changes in design philosophy so will take a little longer to be realised. For example, the present generation of multiple-engine diesel trains have more power than they need for part, or occasionally all, of their scheduled journey.

If some engines could be reduced to idle or shut down during parts of the journey when traction demand is low, there is the potential to save fuel and prevent unnecessary CO2 emissions.

Alan Constable is section head, railway systems and infrastructure, at international rail technology consultant Interfleet